In order to realize an organic EL device with excellent luminous efficiency, driving voltage and luminous lifetime, there have hitherto been developed a variety of compounds. For the purpose of enhancing electron injection properties from a cathode, there are proposed compounds containing a heterocyclic structure of every sort as an electron transporting material.
Patent Document 1 discloses compounds having a 1,10-phenanthroline structure or a bipyridine structure. However, luminance, half-lifetime and luminous efficiency of organic EL devices containing these compounds described in the working examples are merely relative values on the basis of organic EL devices using comparative compounds. Actual measured values which enable one to decide whether or not these compounds realize a practically effective EL device performance are not shown.
Patent Documents 2 and 3 disclose anthracene compounds having two 2,2′-bipyridin-5-yl groups. Though the compounds disclosed in Patent Document 3 improve the lifetime, a driving voltage thereof tends to become high.
Though Patent Document 4 discloses anthracene compounds having a 1,10-phenanthrolinyl group, a more improvement in the lifetime is desired.
Patent Documents 5 and 6 describe that benzo[k]fluoranthene compounds having a benzoimidazolyl group or a substituent analogous thereto are used as an electron transporting material.    [Patent Document 1] JP-A-2003-123983    [Patent Document 2] WO2007/086552    [Patent Document 3] JP-A-2009-275013    [Patent Document 4] WO2007/018004    [Patent Document 5] WO2009/148269    [Patent Document 6] KR-A-2009-0059849